The present invention relates generally to an electromachining method and more specifically to an arrangement which can be used to rough machine the airfoils on bladed disks (or so-called blisks) to a near net shape at a high metal removal rate and with a low tooling cost as compared to turning, milling, EDM (electrodischarge machining) or ECM (electrochemical machining).
The electromachining is a technique which utilizes the rotating movement of a profile-shaped electrode to remove material from a work piece by controlled electrical erosion. The kinematics of the machining is analogous to milling or grinding. The tool-electrode is connected to the negative polarity, while the workpiece is connected to the positive polarity of a pulse generator or continuous power supply of direct current. A gap between the electrodes allows for the flow of an electrolyte.
The electrical erosion can be created by electrical breakdown of the electrolyte or vapor-gas layer produced at the machining interface, as well as by instantaneous arcing or transient short-circuits between the electrodes. In all cases, the deciding factor is the electrical current and duration of the erosion process. However, the electrical erosion of the machining surface is relatively course and a large number of craters are formed in the erosion zone. Thus, this technique cannot be used to produce finely machined work pieces.
A first aspect of the Invention resides in an arrangement for machining airfoils on a blisk, comprising: an annular cutting element supported for rotation about an axis of rotation and adapted for the electromachining.
A second aspect of the invention resides in a method of machining airfoils on a blisk, comprising the steps of: driving an annular cutting element to rotate about its axis; supplying the annular cutting element with a supply of electricity; supplying electrolyte to the interelectrode gap between the annular cutting element and; moving the annular cutting element in multiple mutually opposed directions using a programmable control arrangement to erode material from a work piece to form the blisk.
A third aspect of the invention resides in an arrangement for machining airfoils on a blisk, comprising: means for driving an annular cutting element to rotate about its axis; means for supplying the annular cutting element with a supply of electricity; means for supplying the interelectrode gap with a supply of fluid; and means for moving the annular cutting element in multiple mutually opposed directions using a programmable control arrangement to erode material from a work piece to form the blisk.